Pediatrics - General Pediatrics

Bio

Bio

Dr. Wang is the Director of Center for Policy, Outcomes and Prevention. Prior to coming to Stanford in 2011, he was a faculty member at Boston University Schools of Medicine and Public Health. His other professional experiences include working as a management consultant with McKinsey and Company and serving as the project manager for Taiwan's National Health Insurance Reform Task-force. His current interests include: 1) developing tools for assessing and improving the value of healthcare; 2) facilitating the use of mobile technology in improving quality of care; 3) supporting competency-based medical education curriculum, and 4) engaging in healthcare reform.

Abstract

To understand the forces propelling countries to legislate universal health insurance. DATA SOURCE/STUDY DESIGN: Descriptive review and exploratory synthesis of historic data on economic, geographic, socio-demographic, and political factors.We searched under "insurance, health" on MEDLINE and Google Scholar, and we reviewed relevant books and articles via a snowball approach.Ten countries with universal health insurance were studied. For the five countries that passed final universal insurance laws prior to 1958, we found that two forces of "historical context" (i.e., social solidarity and historic patterns), one "ongoing dynamic force" (political pressures), and "one uniqueness of the moment" force (legislative permissiveness) played a major role. For the five countries that passed final legislation between 1967 and 2010, the predominant factors were two "ongoing dynamic forces" (economic pressures and political pressures) and one "uniqueness of the moment" force (leadership). In general, countries in the former group made steady progress, whereas those in the latter group progressed in abrupt leaps.The lessons of more recent successes-almost all of which were achieved via abrupt leaps-strongly indicate the importance of leadership in taking advantage of generalized economic and political pressures to achieve universal health insurance.

Abstract

Pasteurized human donor milk (DM) is recommended by the World Health Organization and American Academy of Pediatrics for preterm infants when mother's own milk is unavailable, yet the extent and predictors of use and criteria for use in US neonatal intensive care units (NICUs) are unknown.This study aimed to evaluate current DM use in US level 3 NICUs and predictors and criteria of use.We sent mail surveys to 302 US level 3 NICU directors. We used multivariable logistic regression to analyze predictors of DM use.Survey response rate was 60%, and 76 of 182 (42%) directors reported DM use. Among DM users, 30% have used DM < 2 years and 55% for 2 to 5 years. Among nonusers, 63% were uncertain of turnaround time when ordering DM, 36% were unclear what guidelines milk banks followed, and 31% were unsure of parent receptiveness. In multivariate analyses, > 800 annual admissions (odds ratio [OR], 4.11; 95% confidence interval [CI], 1.43-11.82; reference ≤ 400 admissions) and location in the Midwest (OR, 3.02; 95% CI, 1.17-7.76) and West (OR, 6.33; 95% CI, 2.28-15.57; reference Northeast) were positively associated with DM use; safety-net hospitals (> 75% Medicaid insurance) were negatively associated (OR, 0.35; 95% CI, 0.14-0.89).Pasteurized human donor milk use is rapidly emerging among US level 3 NICUs. Larger NICUs and those in the West and Midwest were more likely to use DM, while safety-net hospitals were less likely to use DM. Lack of knowledge by medical directors of accessibility, safety, and parental receptiveness may be barriers to DM use.

Abstract

We developed a comprehensive set of quality-of-care indicators for the management of children with infantile spasms in the United States, encompassing evaluation, diagnosis, treatment, and prevention and management of side effects and comorbidities. The indicators were developed using the RAND/UCLA Modified Delphi Method. After a focused review of the literature and guidelines by the study team, an expert panel (nominated by leaders of Child Neurology Society, American Epilepsy Society, and National Institute for Neurologic Disorders) rated the draft indicators anonymously, met face-to-face to discuss each indicator, and rerated the revised indicators on validity, feasibility, and importance. The panel recommended 21 indicators, of which 8 were identified as most likely to have a large positive impact on improving quality of life and/or health outcomes for children with infantile spasms. The proposed indicators can be used to assess and document variations and gaps in quality-of-care and inform future research and quality improvement interventions.

Abstract

OBJECTIVES To understand retinopathy of prematurity (ROP) follow-up care for preterm very low-birth-weight infants (VLBW; <1500 g) in the context of the chronic care model and identify opportunities for improvement under accountable care organizations. METHODS We conducted focus groups and interviews with parents (N = 47) of VLBW infants and interviews with neonatal intensive care unit and ophthalmologic providers (N = 28) at 6 sites in Massachusetts and South Carolina. Themes are reported according to consolidated criteria for reporting qualitative research guidelines. RESULTS Respondents perceived that legal liability and low reimbursement contributed to shortages of ROP providers. Some neonatal intensive care units offered subsidies to attract ophthalmologic providers or delayed transfers to institutions that could not provide ROP examinations and/or treatment. Sites used variable practices for coordinating ROP care. Even at sites with a tracking database and a dedicated ROP coordinator, significant time was required to ensure that examinations and treatment occurred as scheduled. Parents' ability to manage their children's health care was limited by parental understanding of ROP, feeling overwhelmed by the infant's care, and unmet needs for resources to address social stressors. CONCLUSIONS Under accountable care organizations, hospitals and ophthalmology practices should share responsibility for ensuring coordinated ROP care to mitigate liability concerns. To promote integrated care, reimbursement for ROP care should be bundled to include screening, diagnosis, treatment, and appropriate follow-up. Clinical information systems should be enhanced to increase efficiency and limit lapses in care. Self-management tools and connections to community resources could help promote families' attendance of follow-up appointments.

Abstract

Care and outcomes for individuals living with sickle cell disease (SCD) vary across institutions and communities. The Hemoglobinopathy Learning Collaborative (HLC) seeks to improve outcomes across the life course through improvement science. Faculty identified five key drivers of improved outcomes: a strong community network; knowledgeable, proactive individuals, families and providers; reliable identification and follow-up; seamless co-management between primary and specialty care; and appropriate treatment for acute episodes. Using a modified Delphi process, we selected improvement measures aligned with the drivers. Data are collected via a Web-based system linked to a reporting portal. Participating teams include consumers, community organizations and primary and specialty care providers. This commentary reviews the context of SCD in the U.S.; describes the framework, measures, and technology infrastructure already created for the HLC; reports on the early experience of teams; highlights the initiative's challenges and opportunities; and reflects on its implications in the setting of health reform.

Abstract

Despite recent scientific advances, children with sickle cell disease (SCD) continue to experience high mortality and significant morbidity, in part due to variations in the care provided. We sought to identify and compare drivers for quality improvement among clinical staff and parents of children with SCD.We interviewed clinical staff across care settings in an urban teaching hospital to elicit their perspectives on improving care for children with SCD. Concurrently, we invited parents of children with SCD to participate in focus groups to identify their needs. Findings are reported according to Consolidated Criteria for Reporting Qualitative Research guidelines.We conducted 29 interviews with clinical staff and 4 focus groups with parents. Both groups identified the need for effective communication of relevant patient information across disciplines as a key area for improvement. Clinical staff cited standardization of care delivery as a top priority through increased accessibility of pertinent clinical information, enhanced pain assessment and management, and improved availability of clinical decision-making tools. Parents listed the need for increased community awareness about SCD, including school and day care staff, enhanced parental education and peer support, and self-management skills for their children as opportunities to improve pediatric SCD care.Identifying drivers for quality improvement is a critical first step in transforming the care provided to children with SCD. Using a systematic approach that includes eliciting the perspectives of both clinicians and parents may significantly enhance the development of a patient-centered quality improvement agenda.

Abstract

Sickle cell disease (SCD) affects 70 000 to 100 000 people in the United States, and 2000 infants are born with the disease each year. The purpose of this study was to review the quality of the literature for preventive interventions and treatment of complications for children with SCD to facilitate the use of evidence-based medicine in clinical practice and identify areas in need of additional research.We searched the Ovid Medline database and the Cochrane Library for articles published between January 1995 and April 2010 for English-language abstracts on 28 topics thought to be important for the care of children with SCD. We also added pertinent references cited by studies identified in our search. Each abstract was reviewed independently by 2 authors. Data from articles retrieved for full review were abstracted by using a common form.There were 3188 abstracts screened, and 321 articles underwent full review. Twenty-six articles (<1% of abstracts initially screened), which consisted of 25 randomized controlled trials and 1 meta-analysis, were rated as having level I evidence. Eighteen of the 28 topics selected for this review did not have level I evidence studies published. The management and prevention of pain episodes accounted for more than one-third of the level I studies.Although significant strides have been made in the care of children with SCD in the past 2 decades, more research needs to be performed, especially for acute events associated with SCD, to ensure that the health and well-being of children with SCD continues to improve.

Abstract

To study when and how an urgent public health message about a boil-water order reached an urban population after the Massachusetts water main break.In-person surveys were conducted in waiting areas of clinics and emergency departments at a large urban safety net hospital within 1 week of the event.Of 533 respondents, 97% were aware of the order; 34% of those who lived in affected cities or towns were potentially exposed to contaminated water. Among those who were aware, 98% took action. Respondents first received the message through word of mouth (33%), television (25%), cellular telephone calls (20%), landline calls (10%), and other modes of communication (12%). In multivariate analyses, foreign-born respondents and those who lived outside the city of Boston had a higher risk of exposure to contaminated water. New modes (eg, cellular telephones) were used more commonly by females and younger individuals (ages 18 to 34). Individuals who did not speak English at home were more likely to receive the message through their personal networks.Given the increasing prevalence of cellular telephone use, public officials should encourage residents to register landline and cellular telephone for emergency alerts and must develop creative ways to reach immigrants and non-English-speaking groups quickly via personal networks.

Abstract

To develop a set of quality-of-care indicators for the management of children with sickle cell disease (SCD) who are cared for in a variety of settings by addressing the broad spectrum of complications relevant to their illness.We used the Rand/University of California Los Angeles appropriateness method, a modified Delphi method, to develop the indicators. The process included a comprehensive literature review with ratings of the evidence and 2 rounds of anonymous ratings by an expert panel (nominated by leaders of various US academic societies and the National Heart, Lung, and Blood Institute). The panelists met face-to-face to discuss each indicator in between the 2 rounds.The panel recommended 41 indicators that cover 18 topics; 17 indicators described routine health care maintenance, 15 described acute or subacute care, and 9 described chronic care. The panel identified 8 indicators most likely to have a large positive effect on improving quality of life and/or health outcomes for children with SCD, which covered 6 topics: timely assessment and treatment of pain and fever; comprehensive planning; penicillin prophylaxis; transfusion; and the transition to adult care.Children with SCD are at risk for serious morbidities and early mortality, yet efforts to assess and improve the quality of their care have been limited compared with other chronic childhood conditions. This set of 41 indicators can be used to assess quality of care and provide a starting point for quality-improvement efforts.

Abstract

Despite the recent advances made in the care of children with sickle cell disease (SCD), premature mortality, especially among older children and young adults, remains a hallmark of this disease. The lack of survival gains highlights the translational gap of implementing innovations found efficacious in the controlled trial setting into routine clinical practice. Health services research (HSR) examines the most effective ways to finance, organize, and deliver high quality care in an equitable manner. To date, HSR has been underutilized as a means to improve the outcomes for children with SCD. Emerging national priorities in health care delivery, new sources of funding, and evolving electronic data collection systems for patients with SCD have provided a unique opportunity to overcome the translational gap in pediatric SCD. The purpose of this article is to provide a comprehensive HSR agenda to create patient-specific evidence of clinical effectiveness for interventions used in the routine care setting, understand the barriers faced by clinicians to providing high quality care, assess and improve the interactions of patients with the health care system, and measure the quality of care delivered to increase survival for all children and young adults with SCD.

Abstract

To determine whether Early Intervention programs have the capacity to accommodate the expected increase in referrals following the American Academy of Pediatrics' 2007 recommendation for universal screening of 18- and 24-month-old children for Autism Spectrum Disorders (ASD).We conducted a telephone survey of all state and territory early. Intervention coordinators about the demand for ASD evaluations, services, and program capacity. We used multivariate models to examine state-level factors associated with the capacity to serve children with ASD.Fifty-two of the 57 coordinators (91%) responded to the survey. Most states reported an increase in demand for ASD-related evaluations (65%) and services (58%) since 2007. In addition, 46% reported that their current capacity poses a challenge to meeting the 45-day time limit for creating the Individualized Family Service Plan. Many states reported that they have shortages of ASD-related personnel, including behavioral therapists (89%), speech-language pathologists (82%), and occupational therapists (79%). Among states that reported the number of service hours (n = 34) 44% indicated that children with ASD receive 5 or fewer weekly service hours. Multivariate models showed that states with a higher percentage of African-American and Latino children were more likely to have provider shortages whereas states with higher population densities were more likely to offer a greater number of service hours.Many Early Intervention programs may not have the capability to address the expected increase in demand for ASD services. Early Intervention programs will likely need enhanced resources to provide all children with suspected ASD with appropriate evaluations and services.

Abstract

OBJECTIVE To compare the experiences of e-prescribing users and nonusers regarding prescription safety and workload and to assess the use of information from two e-prescribing standards (for medication history and formulary and benefit information), as they are implemented. DESIGN Cross-sectional survey of physicians who either had installed or were awaiting installation of one of two commercial e-prescribing systems. MEASUREMENTS Perceptions about medication history and formulary and benefit information among all respondents, and among e-prescribing users, experiences with system usability, job performance impact, and amount of e-prescribing. RESULTS Of 395 eligible physicians, 228 (58%) completed the survey. E-prescribers (n = 139) were more likely than non-e-prescribers (n = 89) to perceive that they could identify clinically important drug-drug interactions (83 versus 67%, p = 0.004) but not that they could identify prescriptions from other providers (65 versus 60%, p = 0.49). They also perceived no significant difference in calls about drug coverage problems (76 versus 71% reported getting 10 or fewer such calls per week; p = 0.43). Most e-prescribers reported high satisfaction with their systems, but 17% had stopped using the system and another 46% said they sometimes reverted to handwriting for prescriptions that they could write electronically. The volume of e-prescribing was correlated with perceptions that it enhanced job performance, whereas quitting was associated with perceptions of poor usability. CONCLUSIONS E-prescribing users reported patient safety benefits but they did not perceive the enhanced benefits expected from using standardized medication history or formulary and benefit information. Additional work is needed for these standards to have the desired effects.

Abstract

To determine whether eligible extremely-low-birth-weight children (<1000 g) were enrolled in the federally enacted, state-coordinated Early Intervention (EI) program intended to help children with developmental delay or disability regardless of parental income, and the factors associated with enrollment.Retrospective analysis of 884 EI-eligible ELBW children born in South Carolina with birth weight 401 to 999 g, gestation > or =24 weeks, and survival for the first 120 days of life. We created a linked data set with data from Early Intervention (1996-2001), Vital Records (1996-1998), death certificates, and Medicaid. Each child was followed from birth to 3 years old, the program eligibility period.A total of 54% of ELBW children were enrolled in EI at any time from birth to 36 months. Even among children ever enrolled in Medicaid (83% of all ELBW children), only 63% were enrolled in EI. Being born in a multiple gestational birth, having heavier birth weight (750 to 999 g), and having ever enrolled in Medicaid were positively associated with EI enrollment. Among Medicaid patients for whom perinatal data were available, additional risk adjustment showed that EI enrollment was more likely with birth in level 3 hospitals, birth weight 750 to 999 g, Neonatal Medical Index severity level V (most severe), and longer initial length of hospital stay.Only about half of eligible ELBW children in South Carolina were enrolled-much lower than reported elsewhere. Efforts are needed to understand why eligible infants are not being enrolled and to develop strategies to remedy the situation.

Abstract

Quality indicators are systematically developed statements that can be used to assess the appropriateness of specific healthcare decisions, services and outcomes. In this review, the range and type of indicators that have been developed for children in the UK and USA by prominent governmental agencies and private organisations are highlighted. These indicators are classified in an effort to identify areas of child health that may lack quality measures. The current state of health information technology in both countries is reviewed, since these systems are vital to quality efforts. Finally, several recommendations are proposed to advance the quality indicator development agenda for children. The convergence of quality measurement and indicator development, a growing scientific evidence base and integrated information systems in healthcare may lead to substantial improvements for child health in the 21st century.

Abstract

International initiatives increasingly advocate physician adherence to clinical protocols that have been shown to improve outcomes, yet the process-outcome relationship for adhering to breast cancer care protocol is unknown.This study explores whether 100% adherence to a set of quality indicators applied to individuals with breast cancer is associated with better survival.Ten quality indicators (4 diagnosis-related and 6 treatment-related indicators) were used to measure the quality of care in 1378 breast cancer patients treated from 1995 to 2001. Adherence to each indicator was based on the number of procedures performed divided by the number of patients eligible for that procedure. The main analysis of adherence was dichotomous (ie, 100% adherence vs. <100% adherence).The outcome measures studied were 5-year overall survival and progression-free survival, calculated using the Kaplan-Meier method. The Cox's proportional hazard regression model was used for univariate and multivariate analyses.Most patients received care that demonstrated good adherence to the quality indicators. Multivariate analysis revealed that 100% adherence to entire set of quality indicators was significantly associated with better overall survival [hazard ratio (HR): 0.46; 95% confidence interval (CI): 0.33-0.63] and progression-free survival (HR 0.51; 95% CI, 0.39-0.67). One hundred percent adherence to treatment indicators alone was also associated with statistically significant improvements in overall and progression-free survivals.Our study strongly supports that 100% adherence to evidence supported quality-of-care indicators is associated with better survival rates for breast cancer patients and should be a priority for practitioners.

Abstract

Electronic prescribing has been advocated as an important tool for improving the safety and quality of medication use in ambulatory settings. However, widespread adoption of e-prescribing in ambulatory settings has yet to be realized. The determinants of successful implementation and use in these settings are not well understood.To describe the practice characteristics associated with implementation and use of e-prescribing in ambulatory settings.Multi-method qualitative case study of ambulatory practices before and after e-prescribing implementation.Sixteen physicians and 31 staff members working in 12 practices scheduled for implementation of an e-prescribing program and purposively sampled to ensure a mix of practice size and physician specialty.Field researchers used observational and interview techniques to collect data on prescription-related clinical workflow, information technology experience, and expectations.Five practices fully implemented e-prescribing, 3 installed but with only some prescribers or staff members using the program, 2 installed and then discontinued use, 2 failed to install. Compared to practice members in other groups, members of successful practices exhibited greater familiarity with the capabilities of health information technologies and had more modest expectations about the benefits likely to accrue from e-prescribing. Members of unsuccessful practices reported limited understanding of e-prescribing capabilities, expected that the program would increase the speed of clinical care and reported difficulties with technical aspects of the implementation and insufficient technical support.Practice leaders should plan implementation carefully, ensuring that practice members prepare for the effective integration of this technology into clinical workflow.

Abstract

In the US, all states and the District of Columbia have universal newborn screening (NBS) programs for sickle cell disease (SCD), which also identify sickle cell trait (trait). In this project, we surveyed follow-up coordinators, including one in the District of Columbia and two in Georgia, about protocols for stakeholder notification for SCD and trait. The primary outcomes were total number and type of stakeholder informed of a positive screen. We received 52 completed surveys (100% response). Primary care providers (PCPs) (100%), hematologists (81%), hospitals (73%), and families (40%) were the most commonly notified stakeholders of positive SCD screens, while PCPs (88%), hospitals (63%), and families (37%) were most commonly notified for trait. On average, 3.4 stakeholders were notified for a positive screening for SCD, compared to 2.4 stakeholders for sickle cell trait (P < 0.001). In multivariate analyses for SCD, we found a 2.9% increase in stakeholders notified for each additional year of universal screening mandated in a state (95% CI: 1.4-4.4%). For trait, we found an 8.5% increase in stakeholders notified for each additional follow-up staff (95% CI: 1.3-15.7%), and a 1.3% increase for each additional percent of black births in the state (95% CI: 0.1-2.5%). Wide variation exists in stakeholder notification by NBS programs of positive screenings for SCD and trait. This variation may alter the effectiveness of NBS programs by location of birth.

Abstract

The purpose of our work was to determine whether children with very low birth weight (< 1500 g) who are at high risk for vision and hearing problems and enrolled in Medicaid receive recommended follow-up vision and hearing services and to examine predictors of services.We conducted a retrospective analysis of 2182 children born in South Carolina from 1996 to 1998 with birth weights of 401 to 1499 g, gestations of > or = 24 weeks, and survival of > or = 90 days of life. Receipt of services for Medicaid-enrolled children was assessed by using a linked data set that included files from vital records, death certificates, Medicaid, Chronic Rehabilitative Services, and the Early Intervention Program. We assessed the receipt of hearing rehabilitation by 6 months of age for children with nonconductive hearing loss and routine ophthalmologic examination between ages of 1 and 2 years for all children with very low birth weight. Multivariate logistic regression was restricted to ophthalmologic examinations because of sample size.Among children with very low birth weight with nonconductive hearing loss, 20% received hearing rehabilitation by 6 months of age. Twenty-three percent of children with very low birth weight received an ophthalmologic examination between the ages of 1 and 2 years. Limiting our analysis to children < 1000 g or extending the measurement period to 7 months (hearing) and age 3 years (vision) did not substantially increase the percentage of children receiving the services. The receipt of an ophthalmologic examination was associated positively with Medicaid enrollment by the time of hospital discharge and birth in a level-3 hospital and negatively associated with higher birth weight, an Apgar score of > or = 7, and black maternal race. Among children born at < 1000 g, all of whom were eligible for the Early Intervention Program, the receipt of an ophthalmologic examination was positively associated with program enrollment.There is a shortfall in the provision of critical services for children with very low birth weight. These findings reinforce the Institute of Medicine's concerns regarding inadequate outcome data and health care services for preterm infants and support the importance of enrollment in the Early Intervention Program for children with very low birth weight.

Abstract

To develop a set of quality indicators for the neurodevelopmental follow-up care of very low birth weight (VLBW; <1500 g) children.We reviewed the scientific literature on predictors of neurodevelopmental outcomes for VLBW children and the clinical practice guidelines relevant to their care after hospital discharge. An expert panel with members nominated by the American Academy of Pediatrics, the National Institute of Child Health and Human Development, the Vermont Oxford Network, and the California Children's Service was convened. We used a modified Delphi method to evaluate and select the quality-of-care indicators.The panel recommended a total of 70 indicators in 5 postdischarge follow-up areas: general care; physical health; vision, hearing, speech, and language; developmental and behavioral assessment; and psychosocial issues. Of these, 58 (83%) indicators were in preventive care, 5 (7%) were in acute care, and 7 (10%) were in chronic care.The quality indicators cover follow-up care for VLBW infants with various medical conditions. Given the elevated rates of long-term neurodevelopmental disabilities and the potential impact of poor health care, this new set of indicators provides an opportunity to assess and monitor the quality of follow-up care with the ultimate aim of improving the quality of care for this high-risk population.

Abstract

To compare the functional capabilities being offered by commercial ambulatory electronic prescribing systems with a set of expert panel recommendations.A descriptive field study of ten commercially available ambulatory electronic prescribing systems, each of which had established a significant market presence. Data were collected from vendors by telephone interview and at sites where the systems were functioning through direct observation of the systems and through personal interviews with prescribers and technical staff.The capabilities of electronic prescribing systems were compared with 60 expert panel recommendations for capabilities that would improve patient safety, health outcomes, or patients' costs. Each recommended capability was judged as having been implemented fully, partially, or not at all by each system to which the recommendation applied. Vendors' claims about capabilities were compared with the capabilities found in the site visits.On average, the systems fully implemented 50% of the recommended capabilities, with individual systems ranging from 26% to 64% implementation. Only 15% of the recommended capabilities were not implemented by any system. Prescribing systems that were part of electronic health records (EHRs) tended to implement more recommendations. Vendors' claims about their systems' capabilities had a 96% sensitivity and a 72% specificity when site visit findings were considered the gold standard.The commercial electronic prescribing marketplace may not be selecting for capabilities that would most benefit patients. Electronic prescribing standards should include minimal functional capabilities, and certification of adherence to standards may need to take place where systems are installed and operating.

Abstract

Commercially available electronic prescribing systems may differ in their effects on patients' health outcomes and on patients' ability to manage costs. An expert panel convened to recommend specific features that would enable electronic prescribing systems to advance these goals. The panel authored sixty recommendations and rated each using a modified Delphi process. Ratings identified fifty-two recommendations as clearly positive for patient safety and health outcomes and forty-three recommendations as achievable in the average clinician's office within three years. Overall, these recommendations offer a synthesis of evidence and expert opinion that can help guide the development of electronic prescribing policy.

Abstract

Previous studies from America and Japan have reported that salivary amylase activity was reduced in the elderly. In contrast to these studies, a recent Chinese study reported an increase in salivary amylase activity in the aged. Our study examined approximately equal numbers of Chinese and non-Chinese Americans. The concentration of salivary amylase was estimated from the activity obtained with a colormetric coupled assay utilizing 4NP-G7. Activity was found to be increased in the aged. Our data are discussed with respect to the claims of the previous studies.